LSO/LYSO Crystals for Future High Energy Physics Experiments Rihua Mao, Liyuan Zhang, Ren-Yuan Zhu California Institute of Technology

Introduction LSO/LYSO is a bright (200 times of PWO) and fast (40 ns) crystal scintillator. It has been widely used in medical industry for the PET application with mass production capability exits in the world. The Caltech group has been investigating this material for HEP applications since 2005. It was found that its radiation hardness is excellent against –ray and neutrons. Work by the ETH group also found that it is radiation hard against protons. It thus is an excellent material for HEP & NP experiments in a severe radiation environment, e.g. SLHC. References: IEEE Trans. Nucl. Sci. NS-52 (2005) 3133-3140, Nucl. Instrum. Meth. A572 (2007) 218-224, IEEE Trans. Nucl. Sci. NS-54 (2007) 718-724, IEEE Trans. Nucl. Sci. NS-54 (2007) 1319-1326, IEEE Trans. Nucl. Sci. NS-55 (2008) 1759-1766 and IEEE Trans. Nucl. Sci. NS-55 (2008) 2425-2341, paper N69-8 @ NSS08, Dresden, paper N32-3, N32-4 and N32-5 @NSS09, Orlando. 11/29/2018

Crystals for HEP Calorimeters NaI(Tl) CsI(Tl) CsI BaF2 BGO LYSO(Ce) PWO PbF2 Density (g/cm3) 3.67 4.51 4.89 7.13 7.40 8.3 7.77 Melting Point (ºC) 651 621 1280 1050 2050 1123 824 Radiation Length (cm) 2.59 1.86 2.03 1.12 1.14 0.89 0.93 Molière Radius (cm) 4.13 3.57 3.10 2.23 2.07 2.00 2.21 Interaction Length (cm) 42.9 39.3 30.7 22.8 20.9 20.7 21.0 Refractive Index a 1.85 1.79 1.95 1.50 2.15 1.82 2.20 Hygroscopicity Yes Slight No Luminescence b (nm) (at peak) 410 550 420 310 300 220 480 402 425 ? Decay Time b (ns) 245 1220 30 6 650 0.9 40 10 Light Yield b,c (%) 100 165 3.6 1.1 36 4.1 21 85 0.3 0.1 d(LY)/dT b (%/ ºC) -0.2 0.4 -1.4 -1.9 -0.9 -2.5 Experiment Crystal Ball BaBar BELLE BES III KTeV (L*) (GEM) TAPS L3 BELLE KLOE-2 SuperB SLHC? CMS ALICE PANDA HHCAL? a. at peak of emission; b. up/low row: slow/fast component; c. QE of readout device taken out. 11/29/2018

Producers of Large Size Samples CTI Molecular Imaging (CTI), USA Crystal Photonics, Inc. (CPI), USA Saint-Gobain Ceramics & Plastics, Inc. (Saint-Gobain), France Shanghai Institute of Ceramics (SIC), China Sichuan Institute of Piezoelectric and Acousto-optic Technology (SIPAT), China 11/29/2018

LSO/LYSO Mass Production CTI: LSO CPI: LYSO Saint-Gobain LYSO

SIC LYSO Crystals 1.5 x 1.5 x 12 cm 11/29/2018

SIPAT Ø60 x 250 mm LYSO Ingots 11/29/2018

LSO & LYSO Samples 2.5 x 2.5 x 20 cm (18 X0) CTI LSO CPI LYSO Saint-Gobain LYSO SIPAT LYSO 11/29/2018

Excitation, Emission, Transmission Black Dots: Theoretical limit of transmittance: NIM A333 (1993) 422 LSO LaBr3 LYSO LaCl3 LSO/LYSO has Self-absorption, so are LaBr3 and LaCl3 11/29/2018

L.O. Temperature Coefficient Temperature Range: 15 - 25ºC LSO/LYSO: -0.2%/oC temperature coefficient 11/29/2018

LSO/LYSO with PMT Readout 11% FWHM resolution for 22Na source (0.511 MeV) 40 ns decay, 5/230 times light yield of BGO/PWO 11/29/2018

LSO/LYSO with APD Readout 26% FWHM resolution for 22Na source (0.511 MeV) 4/230 times light yield of BGO/PWO, Readout Noise: < 40 keV 11/29/2018

Excellent Linearity: > 0.511 MeV Observed with 2 x Hamamatsu S8664-55 APD readout 11/29/2018

No scintillation damage under -Rays No damage in photo-luminescence and uniformity after 8,160 Gy from a 137Cs source @ 8,500 rad/hr. 11/29/2018

-Ray Induced Transmittance Damage 300oC thermal annealing effective Transmittance recovery slow 11/29/2018

Radiation Damage under -Rays All samples show consistent radiation resistance EWLT damage: 8% @ 1 Mrad 10% - 15% loss by PMT & APD 11/29/2018

Damage under Fast Neutrons After a fluence of 6×108 n/cm2 from an Am241-Be source no evident damage was observed in the longitudinal transmission and light output. SIPAT-LYSO-L2 SG-L2 LYSO

Radiation Damage under Protons G. Dissertori, D. Luckey, P. Lecomte, Francesca Nessi-Tedaldi, F. Pauss, Paper N32-3@NSS09, Orlando. After 1013 protons/cm2 the induced absorption of LYSO is five times less than that of PWO. 11/29/2018

Light Response Uniformity 25 x 25 x 200 mm samples measured for their L.R.U. and fit to a linear function CTI – L1 SG – L3 SIC – L1 SIPAT – L1 SIPAT – L5 SIPAT – L6 11/29/2018

L.R.U. by PMT & LAAPD: SG-LYSO-L3 Consistent uniformities between PMT and APD Some difference between two end-couplings 11/29/2018

L.R.U. by PMT & LAAPD: SIPAT-LYSO-L5 Issue: Ce doping was optimized for the uniformities measured by PMT with two end-couplings, but a large difference observed between the PMT & APD readouts. 11/29/2018

Radio-luminescence for LSO/LYSO Crystal wrapped with Tyvek paper; ɣ-ray shooting at two ends (1 cm); PMT: XP2254B running @ -1800V. 11/29/2018 22

Radio-luminescence Found: SIPAT-LYSO-L5 has an extra green emission component at the tail end, which does not show in other samples. This may explain the large difference observed in uniformities measured by PMT and APD. The details of this study has been published in IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 55, NO. 3, JUNE 2008 p1759 11/29/2018 23

L.R.U. by PMT & LAAPD: SIPAT-LYSO-L6 SIPAT-LYSO-L6: Consistent slopes for PMT and APD readout. They may be compensated by the optical focusing effect. October 29, 2009

LSO/LYSO ECAL Performance Less demanding to the environment because of -0.2%/oC T coefficient. This material seems the best in terms of radiation hardness among all crystals. A better energy resolution, (E)/E, at low energies than L3 BGO and CMS PWO may be achieved because of its high light output and low readout noise: 2.0 0.5 .001/E 11/29/2018

Summary LSO/LYSO crystals with bright, fast scintillation and excellent radiation hardness is a good candidate material for HEP & NP experiments in a severe radiation environment. The quality of LYSO crystals is adequate for low energy applications, such as KLOE-2 and SuperB. R&D work is needed to further develop crystals for a severe radiation environment, such as SLHC, including growth of crystals of adequate length/size cost-effectively and improving the longitudinal light response uniformity (Ce concentration & self-absorption etc.) and radiation hardness. 11/29/2018